React.js Uncaught Error: Invariant Violation

After getting frustrating from the react_rails gem because of the lack of support for Commonjs modules, i'm testing the react_webpack_rails gem from netguru. but since then i got an Invariant Violation.

For example, if i'm writing a simple Hello World component in ES6 syntax :

You can export the class inline and create the state, which can cause issues. Also notice I changed the name to start with a capital letter TasksBox instead of tasksBox as React wants your class name to start with a capital letter